1) Field of the Invention
The present invention relates to a handy thermal head printer.
2) Description of the Related Art
FIG. 7 is a partially cut perspective view of a conventional printer 10. The printer 10 is handheld by a user and has the function of printing electricity bills, product sales information or the like. This printer 10 has a main body 11 that houses a printer substrate (not shown). This printer substrate holds a control unit (not shown) that controls the printing process.
The main body 11 has a clam-type printer unit 12 provided at one end 11a thereof. The printer unit 12 has a lower cover 13 and an upper cover 14. The lower cover 13 and the upper cover 14 are joined at a joint 15 so that the upper cover 14 can be freely opened and closed. As shown in FIG. 8, which is a cross sectional view of the printer 10 along the line A–A′ shown in FIG. 7, a roll paper R1 is loaded in the hollow space between the lower cover 13 and the upper cover 14, when the lower cover 13 and the upper cover 14 are closed. The roll paper R1 is ribbon-shaped thermal paper and it is wound around a shaft.
Marks are printed beforehand at predetermined intervals near at least one of the longitudinal borders of the roll paper R1 on the printable surface. The marks correspond to the positions where printing is to be started (hereinafter “printing start position”) and where printing is to be stopped (hereinafter “printing end position”). From hereon, the printable surface of the roll paper R1 is the front surface on which information is printed and a non-printable surface is the backside of the roller paper R1 on which information is not printed.
As shown in FIG. 7, the upper cover 14 has a platen roller 16 provided at an end 14a thereof. This platen roller 16 can rotate freely. The main body 11 also has a thermal head 18 provided at the end 11a thereof. This thermal head 18 faces the platen roller 16. During printing, the platen roller 16 sequentially transfers the roll paper R1, held between a thermal head 18, for a distance equivalent to one line. The platen roller 16 is driven by a motor (not shown) by means of a gear (not shown).
The main body 11 further has a mark detecting sensor 17 provided at the end 11a thereof. The mark detecting sensor 17 consists of a light emitting element and a light receiving element. The mark detecting sensor 17 serves to detect the presence of the marks on the printable surface of the roll paper R1.
More specifically, an infrared light or the like is irradiated from the light emitting element towards the printable surface. The mark detecting sensor 17 detects the marks based on the amount of light received by the light receiving element. The mark detecting sensor 17 is connected to a control unit (not shown).
As shown in FIG. 8, when the upper cover 13 is closed, the thermal head 18 is pressed against the platen roller 16 with the roll paper R1 sandwiched therebetween. The thermal head 18 has a number of heating elements placed along its length. These heating elements print dots in one line on the roll paper R1. The thermal head 18 prints the data in the form of dots on the printable surface of the roll paper R1 by applying heat to the roll paper R1.
The roll paper R1 is set in the conventional printer 10 with the following procedure. The person (hereinafter “user”) who is loading the roll paper upper cover 14 opens upper cover 14 and loads the roll paper R1 in the hollow space between the lower cover 13 and the upper cover 14.
Then the user passes the end of the roll paper R1 through the lower cover 13, a guide area 13a, and a mark detecting sensor 17 and, pulls the end till the thermal head 18. Then the user closes the upper cover 14. In this state, the platen roller 16 is pressed against the thermal head 18 with the roll paper R1 sandwiched therebetween, and the end of the roll paper R1 protrudes beyond an opening (hereinafter “ejection”) 19 from where the roll paper R1 is ejected out.
When printing, the control unit drives the motor and rotates the platen roller 16 for a distance equivalent to one line. As a result, the roll paper R1, of length equivalent to one line, is sequentially ejected from the ejection 19.
When the marker detection sensor 17 detects a mark on the printable surface of the roll paper R1, it informs (i.e., sends a signal to) the control unit of the detection of the mark. The control unit identifies the position of the mark as the printing start position and instructs the thermal head 18 to print data on the printable surface of the roll paper R1 in an area other than the area (hereinafter “non-printable area”) of the roll paper R1 from the border to where the marks are printed.
When the mark detecting sensor 17 detects the next mark, it informs the control unit of the detection of the mark. The control unit identifies the position of the mark as the printing end position and stops the motor to thereby stop the rotation of the platen roller 16. In this manner, data is printed between the marks on the printable surface of the roll paper R1.
However, as marks are printed beforehand on the printable surface of the roll paper R1, the non-printable area can not be used for printing. In other words, in this conventional printer 10 there is a problem in that the area where printing can be done is restricted to the area other than the non-printable area.
FIG. 9 shows another conventional printer 20 that solves the problems in the conventional printer 10. FIG. 9 is a partially cut perspective view of the external configuration of the conventional printer 20.
The printer 20 has a main body 21 that houses a print substrate (not shown). This print substrate further holds a control unit (not shown) that controls the printing process.
The main body 21 has a clam-type printer unit 22 provided at one end 21a thereof. The printer unit 22 has a lower cover 23 and an upper cover 25. The lower cover 23 and the upper cover 25 are joined at a joint 24 so that the upper cover 25 can be freely opened and closed.
As shown in FIG. 10, which is a cross sectional view of FIG. 9 along the line B–B′, a roll paper R2 is loaded in the space between the lower cover 23 and the upper cover 25, when the lower cover 23 and the upper cover 25 are closed. The roll paper R3 is ribbon-shaped thermal paper and it is wound around a shaft.
Marks are printed beforehand at predetermined intervals near at least one of the longitudinal borders of the roll paper R2 on the non-printable surface. Similar to the roll paper R1 shown in FIG. 8, these marks correspond to the printing start position and the printing end position.
The main body 21 has a platen roller 26 provided at the end 21a thereof, such that the platen roller 26 can rotate freely. As shown in FIG. 10, the platen roller 26 serves to transfer the roll paper R2 that is held between the thermal head 18, along a single line.
The platen roller 26 is driven by a motor (not shown) by means of a gear (not shown). A knob 27 is provided to one end of the platen roller 26 and this knob 27 is used for manually rotating the platen roller 26.
As shown in FIG. 10, the main body 21 has a mark detecting sensor 28 provided at the end 21a thereof, such that the mark detecting sensor 28 is located near the platen roller 26. The mark detecting sensor 28 detects the presence of the marks on the non-printable surface of the roll paper R2. The mark detecting sensor 28 is connected to the control unit (not shown).
The main body 21 further has a thermal head 29 near the platen roller 26. When the upper cover 25 is closed over the lower cover 23 and the roll paper R2 is loaded in the space therebetween, the thermal head 29 presses against the platen roller 26 with the roll paper R2 sandwiched therebetween. The thermal head 29 has a number of heating elements placed along its length. These heating elements print dots in one line on the roll paper R2. The thermal head 29 prints data in the form of dots on the printable surface of the roll paper R2 by applying heat to the roll paper R2.
In comparison with the printer 10 shown in FIG. 8, in the printer 20, it is possible to increase the printable area of the roll paper R2, as the marks are printed on the non-printable surface, and not on the printable surface.
The roll paper R2 is set in the conventional printer 20 with the following procedure. The user opens the upper cover 25 and loads the roll paper R2 in the hollow space between the lower cover 23 and the upper cover 25.
Then the user passes the end of the roll paper R2 through the lower cover 23, a guide screen 23a, and the mark detecting sensor 28 and pulls the end of the roll paper 20 till the roll paper R2 is sandwiched between the platen roller 26 and the thermal head 29.
Then the user rotates the knob 27 such that the roll paper R2 is transferred in the direction of the ejection 19.
When printing, the control unit drives the motor and thereby rotates the platen roller 26 for a distance equivalent to a line. As a result, the roll paper R2, of length equivalent to one line, is sequentially ejected from the ejection 19.
When the mark detecting sensor 28 detects a mark on the non-printable surface of the roll paper R2, it informs the control unit of the detection of the mark. The control unit identifies the position of the mark as printing start position and instructs the thermal head 29 to print data on the printable surface of the roll paper R2.
When the mark detecting sensor 28 detects the next mark, it informs the control unit of the detection of the mark. The control unit identifies the position of the mark as printing end position and stops the motor to thereby stop the rotation of the platen roller 26. In this manner, the data is printed on the printable surface of the roll paper R2.
However, in the conventional printer 20, as the platen roller 26 is provided at the end 21a, in comparison with the printer 10, there is a difficulty in loading the roll paper R2.
FIG. 11 shows another conventional printer 40 that solves the problems that were there in the conventional printers 10 and 20. In this printer 40, a roll paper that has the mark printed on the non-printable surface is used, moreover, the platen roller is arranged near the upper cover. FIG. 11 shows a cross sectional view of the printer 40.
The printer 40 has a main body 41 that houses a print substrate (not shown). This print substrate further holds a control unit (not shown) that controls the printing process.
The main body 41 has a clam-type printer unit 42 that has a lower outer cover 43 and an upper outer cover 44. The lower outer cover 43 and the upper outer cover 44 are connected by a joint 52 such that the upper outer cover 44 can be freely opened and closed.
A lower inner cover 45 and an upper inner cover 46 are provided on the inside of the lower outer cover 43 and the upper outer cover 44, respectively.
A roll paper R3 is loaded in the space between the lower outer cover 43 and the upper outer cover 44. The roll paper R3 is ribbon-shaped and it is wound around a shaft. One end of the roll paper R3 is R3a, the printable surface is R3b and the non-printable surface is R3c. 
Marks are printed beforehand at predetermined interval near at least one of the longitudinal borders of the roll paper R3 on the non-printable surface R3c. These marks correspond to the printing start position and the printing end position.
The upper outer cover 44 is provided with a platen roller 49 attached to an end 44a thereof, such that the platen roller 49 can rotate freely. During the printing process, the platen roller 49 sequentially transfers the roll paper R3 that is held between the thermal head 51 for a length equivalent to one line. The platen roller 49 is driven by a motor (not shown) by means of a gear (not shown).
The upper outer cover 44 is provided with a mark detecting sensor 50 attached to the end 44a thereof, such that the mark detecting sensor 50 is located near the platen roller 49. The mark detecting sensor 50 detects the marks on the non-printable surface R3c. The mark detecting sensor 50 is connected to the control unit (not shown) through a cable 47. The cable 47 is placed in a space between the lower inner cover 45 and the upper inner cover 46.
The main body is provided with a thermal head 51 that faces the platen roller 49. When the lower outer cover 43 and the upper outer cover 44 are closed, the thermal head 51 presses against the platen roller 49 with the roll paper R3 sandwiched therebetween. The thermal head 51 has a number of heating elements placed along its length. These heating elements print dots in one line on the roll paper R3. The thermal head 51 prints data in the form of dots on the printable surface R3b of the roll paper R3 by applying heat to the roll paper R3.
The roll paper R3 is set in the conventional printer 40 with the following procedure. The user opens the covers 43, 44, 45, and 46 and loads the roll paper R3 in the hollow space between the lower outer cover 43 and the lower inner cover 45.
Then the user passes the end R3a of the roll paper R3 through the lower inner cover 45 and the mark detecting sensor 50 and pulls the end till the thermal head 51. Then the user closes the upper inner cover 46 and the upper outer cover 44. In this state, the platen roller 49 presses against the thermal head 51 with the roll paper R3 sandwiched therebetween and end R3a of the roll paper R3 protrudes beyond an opening from where the roll paper R3 is ejected out.
When printing, the control unit drives the motor and rotates the platen roller 49 for a distance equivalent to one line. As a result, the roll paper R3, of length equivalent to one line, is sequentially ejected.
When the mark detecting sensor 50 detects a mark on the non-printable surface R3c, it informs the control unit of the detection of the mark. The control unit identifies the position of the mark as the printing start position and instructs the thermal head 51 to print data on the printable surface R3b of the roll paper R3.
When the mark detecting sensor 50 detects the next mark, it informs the control unit of the detection of the mark. The control unit identifies the position of the mark as the printing end position and stops the motor to thereby stop the rotation of the platen roller 49. In this manner, data is printed on the printable surface R3b of the roll paper R3.
The Japanese Patent Laid-Open Publications 2000-338822 and 2002-123151 disclose other conventional printers.
In the printer 40 shown in FIG. 11, the upper outer cover 44 is provided with the platen roller 49 and the mark detecting sensor 50 attached at the end 44a thereof. As a result, in comparison with the printer 20, the printer 40 has a merit that the roll paper can be loaded easily. Moreover, the conventional printer 40 uses a roll paper that has the marks printed on the non-printable surface thereof. As a result, in comparison with the printer 20, the printer 40 has a merit that the printable area can be increased.
However, in the printer 40, since the mark detecting sensor 50 is located at the end 44a of the upper outer cover 44, the cable 47 has to be wired in a space between the inner surface and the outer surface of the printer 42. As a result in the printer 40, the printer unit 42 has to be made a twofold structure to accommodate the cable 47 and, therefore, the cost increases.
In addition, the printer unit 42 and the main body 41 are configured as a single unit. Therefore, if the printer unit 42 drops from the hand of the user, the entire unit is damaged. Hence, there is a problem that high cost is incurred as the entire unit must be replaced in case of damage.
Further, the cable 47 bends when the printer unit 42 is repeatedly opened and closed, often causing the breakage of the cable 47. Hence the printer becomes less reliable due to damage of the cable 47.